The 2021 AFC Cup group stage was played from 14 May to 24 August 2021. A total of 38 teams should have competed in the group stage to decide the 12 places in the knockout stage of the 2021 AFC Cup.
<section begin=Draw /> The draw for the group stage was held on 27 January 2021, 14:30 MYT (), at the AFC House in Kuala Lumpur, Malaysia. The 38 teams were drawn into nine groups of four and one group of three (in the Central Asia Zone): three groups each in the West Asia Zone (Groups AâÂÂC) and the ASEAN Zone (Groups GâÂÂI), two groups in the Central Asia Zone (Groups EâÂÂF), and one group each in the South Asia Zone (Group D) and the East Asia Zone (Group J). For each zone, teams were seeded into four pots and drawn into the relevant positions within each group, based on their association ranking and their seeding within their association, in consideration of technical balance between groups. Teams from the same association in zones with more than one group (West Asia Zone, Central Asia Zone, and ASEAN Zone) could not be drawn into the same group.<section end=Draw />
Originally, 39 teams entered into the group stage draw, which included the 35 direct entrants and the four winners of the play-off round of the qualifying play-offs, whose identity was not known at the time of the draw. However, after the withdrawal of teams from Oman and Myanmar, and promotion of KayaâÂÂIloilo to AFC Champions League group stage, only 37 teams would compete, including 34 direct entrants, one winner of the play-off round, and two winners of the preliminary round.
<section begin=Format /> In the group stage, each group was played on a single round-robin basis in centralised venues. The following teams advanced to the knockout stage:
<section begin=Tiebreakers /> The teams were ranked according to points (3 points for a win, 1 point for a draw, 0 points for a loss). If tied on points, tiebreakers were applied in the following order (Regulations Article 8.3):
The schedule of each matchday was as follows.
On 1 March 2021, AFC confirmed the hosts for the group stage, except for Group G whose hosts were decided later.